The hierarchical constraint characteristics of ultra-high molecular weight polyethylene (UHMW-PE) fibers with different structures were evaluated by in situ wide-angle X-ray diffraction (WAXD) measurement during heating. Two UHMW-PE fibers were used in this study, an original gel-spun fiber and a processed fiber that was tensile-drawn from the original fiber above the static equilibrium melting temperature of PE. A difference in fiber processing induced change in constraint distribution attributed to morphological heterogeneity. The original gel-spun fiber, which had a heterogeneous structure, induced the constraint distribution because of the obvious existence of skin and core. In contrast, the tensile-drawn fiber, which had a homogeneous structure formed by the fusion adhesion between twisted single yarn surfaces, depressed the constraint distribution. These results demonstrate that a difference in fiber processing induces change in hierarchical characteristics with different structural dimensions.